Method of manufacturing plaster board



Patented Nov. 30, 1926.

UNITED STATES FRANK GRIS'WOLD, F PORT CLINTON. OHIO,

ASSIGNQR T0 Til-IE AM'ERIGAN GYPSUIVSL' COMPANY, 01? PORT CLINTON, OHIO, A CQRPORATIUN 0T3 OHIO.

METHOD OF MANUFACTTJ'RING IPLASTER BOARD.

No Drawing. Application filed July 27,

This invention relates to improvements in method of manufacturing plaster board and more particularly to a novel process of treating the materials during the manu- 5 facturing of the product to secure better and more uniform. quality.

Plaster board is a well known building material, consisting in. its most common form, of a layer of stucco or plaster interposed between covering sheets of a suitable 'gradeof paper. Plaster board is manufactured commercially by machinery designed to produce the board by a continuous process whereby the paper is fed from rolls into themachine, the stucco ina plastic state introduced between the sheets and the assembledmaterials. passed between forming rolls which reduce the product to a uniform thickness. The board in its wetstatc is then carried for a distance on a horizontal con-' veyor to give the stuccoancpportunity to set, and is then cut into sheets of convenient size, and finally dried in kilns.

2 process of manufacture does not take into consideration the difiiculties that are encountered, due. to the irregularities in quality and condition of materials. In the first place, the problem of adhesion between the paper and stuccois a difiicult one to control.

Under ideal conditions this would be satisfactorily accomplished by a partial saturation of the paper by the moisture in the stucco and the formation of a natural bond between the surfaces. However, it is a diflicult matter to regulate the amount of saturation or quantity of moisture in the stucco for the reason that the paper supply is seldom of a uniform quality,-difl'erent grades 40 or variations in the treatment of the paper having a'marked eti'ect on the properties of the paper to absorb moisture. If the paper absorbs he moisture readily, there is a possibility of over-saturation and a weakenin of the paper structure. On the other hand, under-saturation results in poor adhesion betweenthe materials. Either condition is detrimental to the finished board, since oversaturation produces a weak product, and under-saturation produces an inelfective bond, with the result that the paper peels from the stucco after-the board is dried so that it is either useless or of a very inferior grade.

The purpose of this invention is there- 111 such a way as to eliminate all contact with the stucco to supply the adhesive Theforegoing brief description'of the 1923. Serial N0. 654,265.

fore to devise a method of treating the materials, preferably the surface of the paper, v uncertainties of quality and conditions, by providing a mechanical adhesionor bond between the surface of paper and stucco that will be uniform and effective, thus making it pos sible: to produce a superior product without loss, and of increased strength.

'In. a few words the process consists of applying a water-resisting and adhesive composition to the surface of the paper coming into contact with the stucco, the application being preferably made as the paper is fed from the rolls and dried, before takes place. The result of treating the surface of the paper is twofold; first, thesurface of the paper is waterproofed thereby reducing the subsequent saturation of the paper; and second,

substance made necessary by the elimination of the natural bond by the water-resisting means.

While numerous compositions may be found suitable for this purpose, experiment has revealed the fact that a solution of gum arabic or acacia, aluminum sulphate and water provides a very satisfactory compo sition for this purpose. The solution prefcrably consists of 5% each of gum arable and aluminum sulphate dissolved in 90% of water, although this proportion may be varied somewhat without affecting theproperties of the solution.

The method of application may be varied to meet different operating conditions, but on the whole, a very satisfactory method is to spray the solution onto the surface of the paper. This can be readily accomplished by suitable atomizing or spraying nozzles directed toward the paper as it leaves the roll, although any means which will spread a thin coating of the liquid composition uniformly over the surface of the aper would be quite as satisfactory.

T e drying of the composition after its applicatlon and before the paper comes into contact with the wet stucco 1S obviously a matter of driving olf the water content of the solution within the shortest space of time permitted by the distance and rate of travel of the paper from'the roll to the point of contact with the stucco. The use of either steam coils or fans, or both, will be found to be quite satisfactory. If steam coils are no used they would be located in the path of the paper just beyond the point of application.

of the waterproofing composition, andin close proximity to the surface so that in passing over the coils the heat efiectively dries the coating. Similarly the fans would be mounted to direct a current of air against the surface of the paper as it advances to ward the machine, and. where both steam coils and fans are used, the fans would direct the currentof air through the coils and against the surfaces to be dried. Since there are ordinarily two surfaces to be coated, namely, the inner surface of the top and bottom sheets, the composition applying and drying devices may be arranged to care for both or separate devices provided for each sheet.

Subsequent to the drying process, the paper is brought into contact with the. wet stucco, and passed through the rolls in the usual manner. it follows that the coating is again moistened to create the adhesion or bond between the surfaces of paper and stucco which becomes permanent when the board is subsequently dried.

Under some conditions the process may include the sprinkling of fine sand or other pulverized substance over the surface to which the adhesive composition has been applied, and before it is dried. This material affords a roughened surface and therefore a more complete bond between the paper and the stucco.

By the treatment of the paper with a coating of a composition such as herein set forth, a mechanical bond is established between the materials which is not dependenton the quality of the paper or upon the amount of moisture contained in the stucco in order to secure effective adhesion between the surfaces. This feature of the process, therefore, suggests that dilierent grades of paper can be used without considering its ability to adhereto the stucco thus widening the range of materials available for making the product aeoaaea herein disclosed.

I claim as my invention:

1. A process of manufacturing plaster board consisting of treatin the inner surfaces of the covering materlal with a liquid composition of gum arabic and aluminum sulphate and introducing; stucco in its wet state between sheets of said covering material.

2. A process of manufacturing plaster hoard consisting of treating the inner surfaces of the covering sheet as it is fed from a roll with a coating of a liquid cornposition of gum arabic and sulphate of aluminum, drying the coating by the application of heat or air, and introducing stucco in its wet state between the sheets.

3. A process of manufacturing plaster board consisting of spraying the inner surfaces of the sheets of covering paper with a solution of substantially five percent (5%) each of gum arabic and aluminum sulphate dissolved in water. drying the sheets and then introducing stucco between said sheets.

l. A. process of manufacturing plaster board consisting of spraying the inner surfaces of the covering sheets as they are fed from the rolls. with a solution of 5% of gum. arabic and 5% of sulphate of aluminum dissolved in 90% of water, drying the surfaces of the sheets by the application of heat or air, or both, and introducing stucco in its wet state between the sheets, subsequent to the drying process.

In witness whereof, l. hereunto subscribe my name this 24t day of July. A. D. 1923.

FRANK d. GRISWULD.

For these rea-. 

